Automatic telephone system



Patented Jan. 18, 1927.

narran STATES AParrsur orrics.

HENRY I-IOVLAND, OF FLUSHING, NEW YORK, ASSIGNOB. TO WESTERN ELECTRICCOM.- PANY, INCORPORATED, OF NEW' YORK, N. Y., A CORPORATON 0F NEW YORK.

AUTOMATIC TELEPHCNE SYSTEM.

Application filed December 29, 1924. Serial N o. I58,592.

This invention relates to machine switching telephone exchange systems,and more particularly to systems employing grounded signaling l'rom thesubstations, and is particularly adapted for systems wherein thesubstations are provided with coin collectors.

The object oll this invention is to permit a calling party to build up aconnection to certain lines, for example, to the 0 operator, withoutdepositing a coin while preventinol the calling subscriber from buildingup a connection to an ordinary line, unless the coin is tirst deposited.

A further object of this invention is to provide means to prevent theextension of a calling line to a desired called line if the callingsubscriber attempts to simulate the deposit of a coin.

In accordance with this invention all lines are reached via a certaingroup of selector switches the ordinary lines via certain levels of saidswitches and the free lines via certain other levels of said switches.Each switch is provided with a test relay which is responsive to thedeposit of a coin at the calling substation on calls to an ordinaryline. This relay in responding prepares the switch to extend theconnection to the subsequent switch or switches of the train. On callsto tree lines an alternative circuit is provided for causing said testrelay to respond and permit the establishing ot a connection with a'free line. 1f for any reason the test relay does not respond due to theabsence of the required circuit condition, the selector switch operatesin accordance with its secondary movement and advances to a settingknown as the 11th rotary step position, where it remains until thecalling substation disconnects.

1n the drawing comprising but a single sheet, the invention isdiagrammatic'ally set forth. The calling substation is represented at 1and a typical called substation at 2. The selector switch S--l is wiredin accordance with this invention and has access to another' selectorswitch S2, which in turn has access to a connector C.

The invention will be more readily understood from a detaileddescription of the operation of the system.

Ordinary ca ZZ.

Vhen the receiver is removed at the substation 1 the brushes 5 and 6 ofthe line v27 and slow to release relay 26 in series.

finder LF are set uponthe terminals 3 and 4 of the calling line in amanner not shown and the connection is'extended to the selector switchS-l, closing a circuit to operate the impulse relay 24k in series withthe polarized relay 13 and the loop of the calling substation 1. Thepolarized relay does not operate at this time due to the fact that thedirection of the flow of current in its winding is not in the properdirection to operate it. Relay 24 operated closes an obvious circuit tooperate slow to release relay 25. A circuit is now closed to operaterelay 19 by way of 54, and 49. Relay 19 operated locks by way of itsarmature 8, conductors 48 and 55 and armature 49 of relay 25 to ground.Relay 19 operated renders the interrupter 9 ineffective. The operationof relay 19 closes an obvious circuit to operate relay 18, which locksunder control of relay 11 and connects ground by way of the retardationcoil 17 and conductor 53 to the line finder LF to prevent the linefinder LF from releasing.

The dial at the calling substationl is now operated and released inaccordance with the lirst digit of the number of thecalled line. As thedial returns to normal the loop at the calling substation 1 isinterrupted, thus producing impulses in the circuit including theimpulse relay 24., which relay follows the impulses. When relay 24releases, a circuit is completed by way of its armature and back contactto operate the primary magnet Relays 25 and 26 are made slow 'torelease, so that they will remain operated during the impulse period.Each time the primary magnet 27 operates, a brush rod (not shown)carrying the brushes 20, 21 and 22 is advanced step by step, inaccordance with the primary movement of the selector switch S-1,depending upon the number of impulses produced by the calling dial.During the first step ot the selector rod, the otinormal Contact springsON are closed, closing a circuit to operate the marginal relay 38. Thiscircuit may be traced under control or" the olf-normal contact springsON, alternate contacts of relay 26 to ground at the lett contact otrelay 25. Relay 38 operated locks under control of the secondary magnet36 and its own right hand armature and front Contact to ground undercontrol ot relay 14. lVhen the dial of the calling substation 1 returnsto normal, relay 24 remains operated and relay 26 releases. Relay 26released closes a circuit to operate the secondary magnet 36 and relay37 in series under.control ot the normal contacts of relay 26 andarmature 49 of relay 25. The operation of the secondary magnet 36advances the brushes 29, 21 and 22 of the selector switch S-l, one stepin accordance with the secondary movement ot the switch. The operationot relay 37 substitutes the winding of relay 23 -for the right windingot relay 24 in series with one side of the calling line loop. It a coinhas been deposited in the coin controlled mechanism at the callingsubstation 1, a circuit will be established from battery, through thewinding of relay 23, winding of marginal relay 72, through a pair ofcontact springs 57 and 58 closed by the deposit of the coin at thesubstation 1, to ground. Relay 23 functions as a test relay and will notoperate unless the ground condition described is encountered. Relay 72being marginal does not operate at this time. Relay 23 operated locks byway oit its inner right hand armature and front contact, and armature 49of relay 25 to ground.

The operation of the secondary magnet 36 opens the lockingl circuit forthe marginal relay 38 which releases, in turn releasing the secondarymagnet 36 and relay 37.

Testing for 6m alle rimk.

The brushes 20, 21, and 22 of the selector switch S-l are now resting onthe terminals associated with the first trunk in the selected trunklevel. XVe will assume that this trunk is busy, in which case relayssimilar to 28 and 29 will be operated, connecting ground to the testterminal corresponding to the terminal 32. Under these circumstances, acircuit is closed to reoperate relay 38. This circuit may be tracedunder control of the ott-normal contact springs ON, armature and backcontact of the secondary magnet 36, normal contacts ot the eleventhrotary step springs, normal contact and armature of relay 14, brush 22,terminal corresponding to 32 to ground. Marginal relay 38 reoperatesover the circuit traced and locks, as previously described, thus closingthe circuit' previously described to operate the secondary magnet 36 andthe relay 37 in series. The operation ot the secondary magnet 36 opensthe locking circuit for the marginal relay 38, which releases, in turn,opening the operating circuit for the secondary magnet 36 and relay 37in series. The operation of the secondary magnet 36 likewise advancesthe brushes '26, 21, and 22 another step in accordance with thesecondary movement of the selector switch S-l. This cycle or' operationcontinues until an idle trunk is found.

We will assume the idle trunk to be 'the one associated with theselector switch S-2, in which case terminal 32 will be 'free fromground. lll/lith the brushes 20, 21, and 22 resting upon the terminals30, 31, and 32, respectively, of t'he selector' switch S-n2,term1 nal 32beingungrounded, a circuit is closed to operate relay 14 in series withmarginal relay This circuit may be traced from battery through thewinding ot relay 38, through the oit-normal contact springs ON,arniature and back contact ot the secondary magnet 36, normal contactsot vhe eleventh. rotary step spring." winding ot relay 14 to ground atarmature 49 oit relay 1t should be observed that while the brush 22 waspassing over the terminals ot busy lines, the ground encountcned onthese terminals short circuited the winding ot the relay 14, but when anidle trunlr is' encountered the absence ot ground on the test terminal32 permits relay 14 to operate in series with relay 38. Relay 38, whichis marginal, will not operate at this time due to the high resistance otthe winding olf relay 14 in series with it. The operation oit relay 14extends the connection to the selector switch S-2 and a circuit is nowclosed to operate the impulse relay 28 in series with the polarizedrelay 13 and the line loop ot' the calling substation 1. Relay 28operates over this circuit, closingan obvious circuit to operateslow-to-release relay 29, thus connect-ing ground to the test terminal32, thence by way of brush 22 to the lower inner armature and frontcontact ot relay 14. The operation of relay 14 disconnects the impulserelay 24 of the selector switch S-l from the circuit. Relay 24 releases,in turn releasing relay 25, but the latter being slow to release remainsoperated long enough to permit suliicient time to elapse for relays 28and 29 to operate and connect ground by way ot the test terminal 32 andthe brush 22 to the winding ot relay 14 before, by the release of relay25, the operating ground for relay 14 is ren'ioved at armature 49 otrelay 25.

The selector switch S-2 is set in the saine general manner as theselector' switcl'l S-L except that the impulse relay 28 is employed tooperate the switch setting mechanism (not shown). The selector switch 82 is set u pon the terminals ot an idle connector switch. which we willassume to be the connector switch C, in which case the brushes 40, 41,and 42 come to rest upon the terminals 50, 51, and 52, and the impulserelay 34 of the connector C is operated in series` with the loop ot thecalling` substation 1, closing an obvious circuit to operate theslow-to-releasc relay 39, which connects ground at its armature 47 tothe test terminal 52 of the connector C, thus providing` a busycondition at the test terminal 52 besides holding the switches S-l andS-2 operated.

The polarized relay 13, which is in series with the various impulserelays 24, 28, and 34 in succession, does not operate because the flowof current through its Winding is not in the proper direction to operatesaid polarized relay.

The called substation 2 is signaled in any desired manner and when thereceiver is removed at the called substation 2, a circuit is closed tooperate relay 33. The operation of relay 33 reverses the direction ofthe flow of current in the loop of the calling substation 1, which is inseries with the impulse relay 34. The polarized relay 13 operates onthis current reversal, closing an obvious circuit to operate relay 12.`Relay 12 in turn closes an obvious circuit to operate relay 16, whichlocks under control o1' relay 18, in series with the retardation coil 17to ground.

Disconnect.

lhen the receiver is replaced at the calling substation 1, relay 34releases, in turn releasing relay 39. The release of relay 39 removesground from test terminals 32 and 52, thus permitting relays 14, 19, and23 to release. The release or' relay 14 closes a circuit to operate therelease magnet 35 of the selector switch S--1, thus restoring the brushrod to the normal position. The release of relay 19 connects theinterrupter 9 in series with the winding of relay 11 under control ofthe right-hand inner armature and front contact oit' relay 18 andarmature 10 of rela 19. Relay 11 operated connects battery of the properpolarity through the lamp 43 and the winding of relay 15 in series,through both sides of the loop of the calling substation 1 in parallel,through the coin disposal mechanism to ground at 58. The coin disposalmechanism operates over the circuit described to collect the coin. Itthe ground condition cont-rolled by the coin is present at the callingsubstation 1 at this time relay 15 will operate, thus providing aholding circuit for relay 18. Relay 18 is made slow to release so thatit does not release immediately when relay 11 operates, but will remainoperated long enough for relay 15 to operate and provide a substituteholding ground in the manner described.

When the brush of the interrupter 9 encounters the insulated segment,relay 11 will release, removing the coin collect current :trom thecalling substation 1, thus permitting the coin mechanism to restore andremove the ground previously provided under control 0i the depositedcoin. When the interrupter 9 again reaches the metal segment, relay 11will reoperate, reconnecting coin disposal current to the line. If thecoin has been properly disposed of, the absence of ground at the callingsubstation 1 prevents relay 15 from reoperating; hence after an intervalof time, relay 18 will release, thu-s removing ground supplied throughthe winding of retardation coil 17 from the conductor 53. The removal ofthis ground permits the line nder LF to release in a `manner not shown.When the brush of the interrupter 9 once more reaches the insulatedsegment of the interrupter, relay 11 releases and the circuit isrestored to normal.

Ordinary call-no cot/nJ depostect.

Let us assume that the calling substation 1 initiates an ordinary call,that is, a call for which a charge is imposed, but fails to deposit acoin before operating the dial at the calling .substation 1. Y

Under' these circumstances, the circuit functions in the mannerpreviously described when a coin was deposited. At the end ot theprimary movement of the selector switch S-1, the test relay 23 isconnected to one conductor of the calling line loop under control ofrelay 37.

No coin having been deposited at the calling substation 1, the groundordinarily encountered will be absent and consequently the test relay 23will fail to operate. Under these circumstances, solid ground at thelefthand front contact of relay 25 through the right-hand. outerarmature and back Contact of the test relay 23 will remain connected tothe test brush 22 of the selector switch S-l. The presence or this solidground on the brush 22 is equivalent to a busy condition y upon the testterminal of every trunk in the group, and the secondary magnet 36 andthe marginal relay 38 will operate in the manner previously describedunder Ordinary call7 and the brushes 20, 21, and 22 will advance inaccordance with the secondary movement of the selector switch S-l untilthe last trunk in the group has been passed over and the brushes are setin what is termed the 11th rotary step position. In this position, thecontact springs designated 11th-41S in the drawing will be operated, andsolid ground at the lett normal contact ot relay l 23 will besubstituted for the ground previously supplied through the winding ofthe dial tone transformer DT.

During the .secondary movement ot' the switch the impulse relay 24 willremain operated through its right winding in .series with the right(non-inductive) winding of relay 37 to battery. When the relay 37releases at the end of the secondary movement of the selector switchS-l, ground which is supplied at the left hand normal Contact of relay23 will be connected to the loop of the calling station 1. Under thiscondition the absence of any tone in the receiver at the substation 1will indicate to the calling station that the call has not progressedproperly due to the failure to deposit a coin in the coin controlledmechanism.

Under these conditions the receiver will be replaced upon the switchhookof the calling substation 1, permitting the selector switch S-l torelease and another call will be initiated 1n the proper manner.

Free calls.

Let us assume, however, that the calling substation 1 desires to obtaina connection with a free line, such, for example, as the Zero operator.In this event the receiver is removed -from the switchhook in the usualway and the dial at the calling station 1 is operated and released inaccordance with the code number of the zero operator, which is usually(l. The selector switch S-l will accordingly be set in accordance withits primary movement upon the proper trunk level which we will assume tobe the th or 0 trunk level, of the switch. On this level the brush 46engages a commutator segment which is connected to conductor 56, thusproviding an alternative path to operate the test relay 23 by way ofarmature 49 and front contact of relay to ground. Relay 23 operatedlocks in the manner previously described. The selector switch now testsfor and .seizes an idle trunk in the manner previously described under`Ordinary call and the connection is extended to the Zero operator,displaying a signal at her position as an indication that a call is inwaiting. Vhen the call is answered by the Zero operator there is nocurrent reversal in the calling line loop, thus preventing relays 13, 12and 1G trom operating. The failure ot relay 16 to operate causes thecurrent supplied to the falling line to dispose ot any coin deposited inthe coin controlled mechanism to be in a direction to operate the coindisposal magnet in such a manner as to cause the return ot the coin.

While for purposes of illustration the brush lo has been described asestablishing a circuit over segment l5 and conductor 56 only on thetenth or zero level of selector S--1, it is evident that by multiplingthe segments corresponding to other levels of the .switch bank, the testrelay 23 may be arranged so that it will operate on any desired level toenable free calls to be made.

It is also evident that the selector switch 5 1 may be arranged so as todistinguish between ground supplied by depositing a coin at the calling'substation 1, which ground being` supplied through the resistance oi thecoin control mechanism is ot comparatively high resistance, and a groundsuch as may be caused by placing a false signal on the line. lThisground is usually o'l con'iparatively low resistance. The selectorswitch may be arranged to meet this condition in any suitable manner.One way ot accomplishing this has been illustrated. The marginal relay72 is shown connected in series with the test relay 23 and provided withan armatureand front contact wired in parallel with the right handouter' armature and bacl contact of the test relay 23. Thus, wheneverthe marginal relay is operated due to the placing ol an improper groundsignalingl condition on the line ot the calling substation 1, theoperation ot the marginal relay. connects ground at its front contact tothe test brush The test relay 23 operates as illustrated in the manneralready described. coil 73 ot suitable resistance approximately equal tothe resistance ot the winding ot' the magnet in the coin controlledmechanism is also inserted in series with the lspring contact 4:5. ltwould obriously be necessary ior the test relay 2C) to be operated andthe marginal relay in eplestion to be normal, in order to permit a callto an ordinary line to progress in the proper manner. To obtain thiscondition on the test relay 23 and the marginal relay referred to, itwould be necessary to apply ground oi the proper resistance to oneconductor ot the line t the callingsubstation 1.

VWhat claimed is:

1. ln a telephone system, calling lines, each operable to establishvarious circuit conditions thereon, called lines, classified as chargelines, other called lines classilied as tree lines, switching' mechanismincluding a selector switch rontrollable by a calling line to build up aconnection to any desired called line, means for preventing saidselector switch iirom functioning in accordance with its normal mode otoperation to build up a connection, and means in said selector switchresponsive to a particular circuit condition established at the callingstation for nulliiying the erl'ect oi said lirst meansl to permit saidselector switch to function in accordance with its normal mode ot'operation to build up a connection to a charge line.

Q. In a telephone system, calling lines, each operable to establishvarious circuit conditions thereon, called lines classilied as chargelines, other cal ed lines classitied as tree lines, switching mechanismincluding a selector switch controllable by a calling line to build up aconnection to any desired called line, means tor preventing saidselector switch t'rom 'functioning in accordance with its normal mode otoperation to build up a connection, means in said selector switchresponsive to a particular circuit condition established at the callingstation for nullitying the effect of said iirst means to permit saidselector switch to 'unction in accordance with its normal mode ofoperation to build up a connection to a charge line, and means in saidselector switch operable irrespective of the circuit conditionestablished on the calling line 'for permitting said selector switch tooperate to build up a connection to a tree line.

3. In a telephonev system, calling lines,

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means associated with each calling line for establishing various circuitconditions thereon, called lines classified as charge lines, othercalled lines classified as free lines. a train of automatic switchesoperable under control of a calling line to build up a connection to anydesired called line, means for preventing said automatic switches fromfunctioning in accordance with their normal mode of operation to buildup a connection, and means in one switch of the train responsive to aparticular circuit condition established at the calling station fornullifying the effect of said preventing means to permit said switch tofunction in accordance with its normal mode of operation to build up inpart a connection to a charge line.

4. In a telephone system, calling lines, means associated with eachcalling line for establishing various circuit conditions thereon, calledlines classified as charge lines, other called lines classified as freelines, a train of automatic switches operable under control of a callingline to build up a connection to any desired called line, means forpreventing said automatic switches from functioning in accordance withtheir normal mode of operation to build up a connection, means in oneswitch ofl the train responsive to a particular circuit conditionestablished at the calling station for nullifying the effect of saidpreventing` means to permit said switch to function in accordancewithits normal mode of operation to build up in part a connection to acharge line, and means in said switch operable irrespective of thecircuit condition established at the calling station for permitting saidswitch to function in accordance with its normal mode of operation tobuild up a connection to a free line.

5. In a telephone system, calling lines, means associated with eachcalling line for establishing various circuit conditions thereon, calledlines classified as charge lines, other called lines classified as freelines, a train of automatic switches operable under control of thecalling line to build up a connection to any 'desired called line, oneof the switches in said switch train having both a primary and asecondary movement, means for preventing said last mentioned switch fromfunctioning in accordance with its normal secondary movement, and meansin said last mentioned switch effective at the end of the primarymovement thereof responsive to a particular circuit conditionestablished at the calling station for nullifying the effeet of saidpreventing means to initiate the secondary movement of said switch inaccordance with its normal mode of operation to build up in part aconnection to a charge line.

.6. In a telephone system, calling lines,

means associated with each calling line for establishing various circuitconditions thereon, called lines classified as charge lines, othercalled lines classified as free lines, a train of automatic switchesoperable under control of the calling line to build up a connection toany desired called line, one ofthe switches in said switch train havinglboth a primary and a secondary movement, means for preventing said lastmentioned switch from functioning in accordance with its normalsecondary movement, means in said last mentioned switch effective at theend of the primary movement thereof responsive to a particular circuitcondition established at the calling station for nullifying the effectof said preventing means to initiate the secondary movement of saidswitch in accordance with its normal mode of operation to build up inpart a connection to a charge line, and means in said switch effectiveat the end of the primary movement thereof irrespective of the circuitcondition established at the calling station for permitting said switchto function in accordance with its normal mode of operation to build upa connection to a free line.

7 In a telephone system, calling lines, a coin controlled mechanismassociated with each calling line, called lines classified as chargelines, other called lines classified as free lines, switching mechanismincluding a selector switch controllable by a callingrline to build up aconnection to any desired called line, means for preventing saidselector switch from functioning in accordance with its normal mode ofoperation, and means in said selector switch responsive to the depositof a coin in the coin controlled mechanism associated with the callingline for nullifying the effect of said first means to permit saidselector switch to operate to build up a connection to a charge line.

8. In a telephone system, calling lines, a coin controlled mechanismassociated with each calling line, called lines classified as chargelines, other called lines classified as free lines, switching mechanismincluding a selector switch controllable by a calling line to build up aconnection to any desired called line, means for` preventing saidselector switch from functioning in accordance with its normal mode ofoperation, means in said selector switch responsive to the deposit of acoin in the coin controlled mechanism associated with the calling linefor nullifying the effect of said first means to permit said selectorswitch to operate to build up a connection to a charge line, and meansin said selector switch operable irrespective of the presence or absenceof a coin in the coin controlled mechanism for permitting said selectorswitch to operate to .build up a connection to a free line.

9. In a telephone system, calling lines,

a coin controlled mechanism associated with eachcalling line, calledlines classified as charge lines, other called lines classiiied as freelines, a train ot automatic switches operable under control ot a callingline to build up a connection to any desired called line, one ot theswitches in said switch train having both a primary and secondarymovement,'1neans for preventing said last men` tioned switch tromJfimctioning in accordance with its normal seconday movement, means insaid last mentioned switch el'tective at the end ot the primaryn'iovement thereof responsive to the deposit ot a coin in the coincontrolled mechanism associated with the calling line tor nullitying theeffect of said tirst means to initiate the secondary movement of saidswitch in accordance with its normal mode of operation to build up inpart a connection to a charge line, and means in said switch operableirrespective ot' the presence or absence of a coin in the coincontrolled mechanism tor initiating the secondary movement of saidswitch in accordance with its normal mode ot operation to build up aconnection to a tree line.

10. In a telephone system, calling lines, a. coin controlled mechanismassociated with each line, a plurality of groups of trunk circuits, anumerical switch operable under control otl a calling line whereby saidswitch may be set opposite any desired trunk group, called linesclassified as charge lines reached via said switch and one ot certain otsaid trunk groups, other called lines classified as free lines reachedvia said switch and one of the remaining trunk groups, means in saidswitch responsive to the depositing of a coin in the coin controlledmechanism associated with the calling line Afor permitting said switchto seize an idle trunk in the trunk group leading to a charge lineopposite which group said switch is set, and means in said switchoperable irrespective of the presence or absence of a coin in the coincontrolled mechanism providing said switch is set opposite a trunk groupleading to a free line tor permitting said switch to seize an idle trunkin said trunk group.

ll. In a telephone systen'i, calling lines, a coin controlled mechanismassociated with each calling line, a plurality of groups of trunkcircuits, a numerical switch operable under control ot the calling linewhereby said switch may be set opposite any desired trunk group` calledlines classified as charge lilies reached via said switch and certain oisaid trunk groups, other called lines classified as tree lines reachedviaA said switch and others of said trunk groups, a relay in said switchoperable responsive to the deposit ot a coin in the coin controlledmechanism `associated with the calling line for permitting said switchto seize' an idle trunk in the trunk group leading to a charge lineopposite which group said switch is set, and means responsive to thesetting ot' said switch opposite a trunk group leading to a free linefor permitting said switch to seize an idle trunk in said trunk group.

l2. ln a telephone system, calling lines, a coin controlled mechanismassociated with each calling line, a plurality ot groups oi trunkcircuits, a numerical switch having a primary and a secondary movementoperable under control of the calling line whereby said switch may beset in accordance with its primary movement opposite any desired trunkgroin), called lines classiiied as charge lines reached via said switchand one of certain ot said trunk groups, other called lines classifiedas tree lines reached via. said switch and one of the remaining trunkgroups, means in said switch responsive to the deposit ot a coin in thecoin controlled mechanism associated with the calling line forinitiating the secondary movement ot said switch in accordance with itsnormal mode ot' operation whereby an idle trunk in any selected trunkgroup may be seized, and means responsive to the selection of a trunkgroup leading to a free line for initiating the secondary movement ofsaid switch irrespective of the presence or absence of a coin in thecoin controlled mechanism associated with the. calling line.

1 3. In a telephone system, calling lines, a coin controlled mechanismassociated with each calling line, a plurality of groups ot trunkcircuits, a numerical switch having a group hunting movement followed bya trunk hunting movement operable under control ot the calling line andhaving access to said trunk groups, a non-numerical switch operableresponsive to the initiating of a call on a calling line for extendingthe calling line to said numerical switch, called lines classihed ascharge lines reached via said switch and one o'l' certain of said trunkgroups, other called lines classified as Jfree lines reached via saidswitch and one of the remaining trunk groups, means in said switchresponsive to the deposit ot a coin in the coin cont-rolled mechanismassociated with the calling line for initiating` the trunlc limitingmovement of the numerical switch in accordance with its normal mode ofoperation, and means responsive to the selection of a trunk groupleading to a free liuc tor initiating the trunk hunting movement ot saidnumerical switch irrespective ot thel presence or absence ot a coin inthe coin controlled mechanism associated with the calling line, aplurality of sources et current capable of being applied to the callingline to dispose of the deposited coin, means responsive to thedisconnection of the calling station i'oi causing one of said currentsources to be applied to the calling line to dispose of the coin, meansfor maintaining said non-numerical switch in operative relation with thecalling line until the coin has been disposed ot, and means effectiveafter the coin has been disposed ot for causing said non-numericalswitch to release the calling line.

14. In a telephone system, calling lines, a coin controlled mechanismassociated with eacli calling line, called lines, switching mechanismcontrollable by a calling line to build up a connection to any desiredcalled line, means for preventing said switching mechanism fromfunctioning in accordance with its normal mode of operation, means insaid switching mechanism responsive to the deposit of a coin in the coincontrolled mechanism associated with the calling line for nulli'fyingthe effect ot said iirst means to permit said switching` mechanism tooperate to build up a connection to a called line, and means in saidswitching mechanism responsive to the simulated deposit of a coin tomaintain the eiect of said iirst means.

15. In a telephone system, calling lines, a coin controlled mechanismassociated with each calling line, called lines, switching mechanismcontrollable by a calling line to build up a connection toany desiredcalled line, means for preventing said switching mechanism fromfunctioning in accordance with its normal mode of operation, a relay insaid switch operable responsive to the deposit of a coin in the coincontrolled mechanism associated with the calling line for nullifying theeEect of said first means to permit said switching mechanism to operateto build up a connection to a called line, and a second relay operableonly when a line condition simulating the deposit of a coin isestablished to maintain the eiect of said first means.

In witness whereof, I hereunto subscribe my name this 26th day ofDecember A. D., 1924.

HENRY HOVLAND.

